State gambling regulators are hiring their own private counsel as they face lawsuits from the cities of Boston, Revere and Somerville over a license awarded to Wynn Resorts for a casino in Everett. The move is an attempt to avoid legal issues that could arise if the attorney general’s office, which represents the state and its agencies, were to defend the Massachusetts Gaming Commission from the civil litigation as the office pursues a criminal case involving the sale of land for the casino.